ANN ARBOR, Mich., April 16 (UPI) -- U.S. scientists say they've resolved a dispute about one of the mechanisms believed responsible for brain cell death and memory loss in Alzheimer's disease.

Assistant Professors Michael Mayer of the University of Michigan and Jerry Yang of the University of California-San Diego said they and their colleagues have clarified how small proteins called amyloid-beta peptides damage brain cell membranes, allowing extra calcium ions to enter the neurons.

The researchers confirmed evidence that amyloid-beta peptides create pores in brain cell membranes, opening channels for calcium ions to enter. This was one mechanism researchers had contemplated, but some scientists had believed the peptide caused a general thinning of the cell membranes and these thinned membranes lost their ability to keep calcium ions out of brain cells.

Mayer and Yang disproved the latter theory.

"This ongoing controversy has slowed our own progress in Alzheimer's research as well as progress in other labs," Mayer said. "It is our hope that putting this disagreement to rest by showing that amyloid beta peptides do not thin membranes, but instead form discrete pores in membrane can help the field move forward at a more rapid pace," Mayer said.

The study that included UM Associate Professor Scott Turner is available online in the Journal of Neurotoxicity Research and will appear in the May print edition.